There is a national program that identifies duplicate names of registered voters from among states that belong to it. It is called the Interstate Crosscheck Program run by the Secretary of State of Kansas.
Here are two sites that explain how it works. The first is a slide presentation of the Program. The second is a sample copy of the recent contract with Pennsylvania.
The program, run by state officials, combines voter lists from member states and locates matches of voters with similar information such as first name, middle initial, last name, birth date, and in states that keep such records, the last four digits of the person’s Social Security number.
The site does nothing more that that. It works with the data supplied by the member state and cooperating employees.
The Interstate Crosscheck Program does not investigate, or prosecute voters who come up as matching a voter in another state. That is left up to the state to do.



